According to the article, what are some instances in which one should refrain from stretching?

These are the instances when you should avoid stretching:
1. when you have had a recent injury otherwise you may worsen the injury further.
2. After surgery especially if it on the Achilles heel or tendon, it is not advisable to stretch, it should be given time to heal.
3.If you are feeling cold. doing so can cause a muscle tear.

Smoking damages the respiratory system by inhalation of a foreign substance, that is absorbed and residue is left behind on our lungs sponge like substance. the gas that is inhaled also increase your blood pressure and dilates your blood vessels. also the process of inhaling and exhaling the smoke it causes irritation to the throat and mouth. smoking can cause lung cancer and other respiratory and circulatory diseases.